I have gone through the Getting Started tutorial for SpecFlow. Everything worked fine except that I have the @SpecRun test because I have not entered a demo key.
But
If you want to your tests - the unit tests generated by Specflow, just for being precise - displayed in your unit test explorer you must create Unit test project. If you created a class library project then you won't see them.
Here you can find information about how you can convert your class library project to unit test project.